1. Field of the Invention
The present invention relates to a washing machine with a float type clutch and a control method for the float type clutch. More particularly, the present invention relates to a washing machine with a float type clutch in which a float connects a rotating force from a motor to a spin-drying shaft or disconnects the rotating force from the spin-drying shaft as it is upwardly or downwardly moved in accordance with supply or drainage of wash water, thereby allowing a washing operation or a dehydrating operation to be carried out, while forming an air layer for preventing wash water from reaching gears included in the float type clutch. The present invention also relates to a clutch control method in the washing machine with the float type clutch which involves an algorithm for determining whether or not the float is engaged with or disengaged from the spin-drying shaft, and executing an engagement or disengagement operation based on the determined result, and an algorithm for discriminating whether or not the engagement or disengagement is achieved in accordance with the float engagement/disengagement determining algorithm, thereby achieving an improvement in the reliability of float engagement/disengagement operations.
2. Description of the Related Art
Generally, a washing machine including a float type clutch has a configuration in which a float is spline-coupled to a wash shaft in such a fashion that it moves vertically along the wash shaft in accordance with supply and drainage of wash water between the bottom of a pulsator and a wash tub, thereby performing switching-on and -off of power supply.
That is, the float is separated from the spin-drying shaft during washing and rinsing operations as it is raised by wash water. Accordingly, the rotating force from the motor is transmitted only to the wash shaft, thereby causing the pulsator to perform washing and rinsing operations while rotating normally and reversely. When the wash water is drained after completion of the washing and rinsing operations, the float is lowered by its weight, so that it is coupled with the spin-drying shaft. Accordingly, the wash tub performs a dehydrating operation as it is rotated in one direction at a high speed.
FIG. 1 is a sectional view illustrating a part of a washing machine with a conventional float type clutch.
The configuration of the washing machine will be described in conjunction with FIG. 1.
As shown in FIG. 1, the washing machine includes a water reservoir tub 12, a wash tub 14 rotatably received in the water reservoir tub 12, and a pulsator 16 mounted to the wash tub 14 in the interior of the wash tub 14 and adapted to wash clothes while rotating normally and reversely in accordance with a rotating force transmitted from a drive motor 22 to a wash shaft 74. The drive motor 22, which is also included in the washing machine, supplies power for rotating the wash tub 14 and pulsator 16. The washing machine further includes a float type clutch 60 for selectively connecting the wash tub 4 and pulsator 16 in accordance with whether or not wash water is present, and a transmission 70 for transmitting the power from the drive motor 22 to the wash tub 14 and pulsator 16. The transmission 70 includes a hollow spin-drying shaft 72 fixedly coupled to the wash tub 14. The wash shaft 74 is also included in the transmission 70. The wash shaft 74 is fixedly coupled at an upper end thereof to the pulsator 16 while being connected at a lower end thereof to the drive motor 22. The transmission 70 also includes a plurality of bearings 76 for supporting the spin-drying shaft 72.
The float type clutch 60 includes a float 62 serration-coupled to the wash shaft 74 in such a fashion that it moves vertically in accordance with supply and drainage of wash water, and a fixed member 63 fixedly mounted to the upper end of the spin-drying shaft 72, and separably coupled with the float 62.
The float 62 includes a hub portion 621 serration-coupled to the wash shaft 74, and a tube portion 622 arranged around the hub portion 621. The hub 621 has a serrated structure at a lower surface thereof, whereas the tube section 622 has a closed hollow structure.
The fixed member 63 has a serrated structure at an upper surface thereof so that it is engaged with the lower surface of the hub portion 621 included in the float 62.
FIGS. 2 and 3 illustrate the operation of the above described washing machine provided with the conventional float type clutch. Now, the operation of the washing machine will be described in conjunction with FIGS. 2 and 3.
When wash water is supplied into the wash tub 14 in accordance with a water supplying operation, the float 62 is raised by the supplied wash water, so that it is separated from the fixed member 63. As a result, the float type clutch 60 is shifted to its power cut-off position, thereby causing the power from the drive motor 22 to be transmitted only to the wash shaft 74.
Thus, a washing operation is begun. When the drive motor 22 operates in accordance with the washing operation, the pulsator 16 connected to the wash shaft 74 is rotated. Since the drive motor 22 performs alternating normal and reverse rotations, the pulsator 16 performs corresponding normal and reverse rotations.
In accordance with the rotating operation of the pulsator 16, a vortex flow of wash water is formed. When the pulsator 16 rotates continuously in one direction for a predetermined time or more, the wash tub 14 is also rotated in the same direction as the pulsator 16 by virtue of the vortex flow of wash water. As a result, a centrifugal force is generated. This centrifugal force acts to outwardly discharge the wash water from the wash tub 14. The discharged wash water is introduced again into the wash tub 14 after passing through a fluid path defined between the wash tub 14 and the water reservoir tub 12. Thus, centrifugal washing in the manner of so called “waterfall washing” can be carried out.
Following the washing operation, rinsing and dehydrating operations are sequentially carried out. Prior to the dehydrating operation, rinsing water used in the rinsing operation is drained. When the rinsing water is drained, the float 62 is lowered by its weight, so that it is engaged with the fixed member 63. That is, the float type 60 is shifted to its power transmission position.
When the wash shaft 74 is rotated in accordance with the operation of the drive motor 22 in this state, the float 62 serration-coupled to the wash shaft 74 is rotated. Accordingly, the fixed member 63 engaged with the hub portion 621 of the float 62, and the wash tub 14 connected to the fixed member 63 are also rotated in the same direction as the wash shaft 74.
As the wash tub 14 rotates rapidly in one direction, a centrifugal force is generated, thereby causing the clothes in the wash tub 14 to come into contact with the inner wall of the wash tub 14. In this state, spin-drying is carried out in accordance with the centrifugal force. That is, the clothes are spin-dried in accordance with the centrifugal force. The moisture removed from the clothes is drained through a plurality of holes 14a formed at the inner wall of the wash tub 14. Since the wash tub 14 rotates in the same direction as the pulsator 16, the clothes are not caught on the pulsator 16. Accordingly, it is possible to prevent the clothes from being damaged by the pulsator 16.
When a washing operation is carried out in the washing machine using the above mentioned float type clutch after the spin-drying operation or under the condition in which no washing has been performed for a prolonged period, the float 62 should be raised by wash water supplied for the washing operation so that it is separated from the fixed member 63, thereby preventing transmission of power to the wash tub 14.
However, this washing machine has a problem in that foreign matters formed from the clothes may be caught on the hub portion 621 of the float 62 or the fixed member 63 as they are outwardly discharged along with the wash water, because there is no structure capable of forming an air layer for preventing the wash water from being introduced between the hub portion 621 of the float 62 and the fixed member 63 when the float 62 is raised in accordance with an increase in the level of the wash water.
Where foreign matters such as lint are firmly caught between the hub portion 621 of the float 62 and the fixed member 63, the engagement between the hub portion 621 of the float 62 and the fixed member 63 may be maintained by a coupling frictional force exceeding the buoyancy of the float 62. In this case, the washing operation may be carried out under the condition in which the float 62 is not separated from the fixed member 63 by the supplied wash water. As a result, the hub portion 621 of the float 62 and the fixed member 63 generate noise while being abraded. Furthermore, the entire rotating structure of the washing machine including the wash tub is rotated, thereby causing the drive motor 22 to be overloaded.
Although the float hub portion of 621 is lowered to engage with the fixed member 63 in the dehydrating operation, the engagement may be inaccurately made. In this case, slippage may occur between gears, thereby causing those gears to be abraded during their rotation for the spin-drying. Furthermore, the gears may interfere with each other, thereby generating considerable noise. In severe cases, it may be impossible to achieve a normal dehydrating operation.